I Spent 2 Weeks Reverse-Engineering Substack's API. Now Claude Runs My Analytics.

I reverse-engineered Substack's internal endpoints and built an MCP server that lets Claude answer analytics questions your dashboard can't. 18 tools, $0 hosting, full build log inside.

Every time I open my Substack dashboard, the numbers are right there. Subscribers. Views. Open rate.

But none of them answer the question I actually care about: what’s working?

Which posts are converting free subscribers to paid? Is my traffic coming from email, search, or Notes shares? Is engagement actually improving, or did I just get lucky on one post?

The data exists. It’s just scattered across a dozen dashboard pages with no way to connect them. You can see your open rate. You can see your traffic sources. You can’t see the line between them.

So I built an MCP server that lets Claude do the analysis for me. 18 tools covering Substack analytics, subscribers, and revenue. Built on Substack’s internal API - the same endpoints that power SubflowAI in production.

This is the full build log - the decisions, the legal research, the moment something broke, and the architecture choice that made everything else simple.

👋 Julley, I'm Dheeraj, an AI systems builder.

I build production-grade AI sy…